On rare occasion, an extraterrestial event, such as a meteorite landing, can create landforms.
The landscape around our planet is diverse and captivating. From the vast ice sheets of Antarctica to the glaciated mountains of Norway, there exist many different landforms that have fascinated scientists and geographers for ages. Even today our understanding of the forces that play a role in the creation of our vast topography is still evolving.
Glaciers
Glaciers are vast sheets of ice that cover many areas on earth. Antarctica is actually an accumulation of numerous glaciers. These sheets of ice expand and shrink in response to long-term climate conditions. When glaciers grow, an accumulation of snow and ice thickens the layer of ice. When glaciers recede, the ice melts and the area that the ice field covers becomes smaller. In either case, a glacier is capable of scouring and sculpting the land in its path. The movement of a glacier is produced by gravity as the ice follows the terrain slowly downhill.
Tectonic Plates
Current plate tectonic theory expresses the idea that both the land and sea areas of the earth sit atop a collection of large tectonic plates that float on the earth's mantle. Each plate is "free floating" so that it is possible for two tectonic plates to move toward each other and collide. These movements occur over millions of year and are responsible for volcanic activity and the uplifting of mountains.
Volcanoes
Volcanoes are large conical earth forms that on occasion are capable of emitting hot gases, ash and molten lava from their apex. The formation and eruption of volcanoes are major geological events that affect our planet in many ways. Besides the large mountainous cones, the lava that flows down the side can create rock formations and new pieces of land. The craters of extinct or dormant volcanoes often are home to freshwater lakes or bowl-shaped valleys called calderas.
Water Erosion
Water running downhill is a powerful geologic force, for it can carve up the terrain where it flows, while carrying sand and silt downstream. The material in the stream will be deposited at the edge of the sea, where it builds up to form sedimentary layers. Over time these layers of sand and silt may rise to form new land masses -- or the oceans may recede to expose the newly created sedimentary rocks.
Meteorites
The study of meteorite craters on earth reveals a fascinating kind of rare landform. It also opens a little-studied topic concerning the effects of orbiting space objects on the surface of our planet.
Tags: areas earth, sand silt, tectonic plates, vast sheets, When glaciers
